1. Field of the Invention
This invention relates generally to soldering irons and soldering stations used in modern electronic production, rework and repair applications which are temperature controlled, and specifically relates more to production type soldering stations which feature a heater which is either replaceable or integral with the soldering handpiece and which utilizes separately replaceable tips which wear during normal use. The invention also relates to such soldering irons and soldering stations which use a combined tip/heater cartridge, and in which the entire tip/heater cartridge is changed when the tip wears out.
2. Description of Related Art
The products the first type mentioned above are produced by WELLER(copyright), PACE(copyright), ANTEX(copyright), ERSA(copyright) and HAKKO(copyright); see also, commonly owned, co-pending U.S. patent application Ser. No. 09/973,952. The products of the second type mentioned above include the tip/heater cartridge product of METCAL INCORPORATED, or a combined heater/thermocouple arrangement such as that found in U.S. Pat. No. 5,043,560 (Masreliez) and in the Model 941 soldering station of the Hakko Corporation (Miyazaki U.S. Pat. No. 6,054,678); see also, U.S. Pat. No. 4,839,501 of METCAL(copyright) and commonly owned, co-pending U.S. patent application Ser. Nos. 09/972,194 and 10/046,545. Compared with traditional soldering stations, tip/heater cartridge stations generally offer significantly improved heat delivery and responsiveness as well as a slim, lightweight and often cooler handpiece which many operators prefer.
Conventional soldering stations for modern, high-reliability electronic production, rework and repair applications (hereinafter, xe2x80x9csoldering stationsxe2x80x9d shall also include xe2x80x9csoldering ironsxe2x80x9d) have become the generally accepted norm due to their ability to maintain a safe, appropriate, user-selected tip operating temperature for the particular application at hand. Such traditional soldering stations generally feature a soldering iron handpiece which consists of a handle and a closed-loop temperature controlled heater onto which a replaceable soldering tip is attached through various means, examples of which include the products made by WELLER(copyright), PACE(copyright) ANTEX(copyright), ERSA(copyright) and HAKKO(copyright). These tip attachment means include a variety of configurations which are well known to the art. One configuration is a hollow heater into which tips are installed and fastened with set screws. Another configuration includes a thin cylindrical heater over which a hollow tip is installed and held in place by a shroud which fits over a shoulder on the tip and is fastened to the handpiece with a nut. Still another tip attachment means includes a thin, cylindrical heater with a stainless steel shroud over which a hollow tip is installed and held fast by some spring means which includes a separate spring ring, a spit in the open end of the tip that fits over the shroud, a combination of these two features or an independent coil spring with one end attached to the handpiece and the other end formed in a small hook shape which when stretched slightly engages a hole in the side of the tip thereby holding it in place.
Most of these conventional soldering stations offer adequate thermal performance, operator comfort and ease of use for older electronic assemblies. In addition, they provide relatively economical operation in that the replaceable tips are generally in the $4.00 to $8.00 dollar range in cost and the heaters need replacement only occasionally. However, when their heaters need replacement, they can be quite costly upwards of $75 dollars each or more and/or can be very time consuming or difficult to replace, often requiring soldering or desoldering. However, some soldering irons feature easily replaceable heaters, such as the PACE PS-80/90 handpieces; but, the cost of heater replacement is still relatively high. Furthermore, with other conventional soldering irons, the heater is not replaceable at all (ANTEX and WELLER SILVER SERIES), so that the entire handpiece must be replaced, sometimes costing upwards of $125 dollars or more.
In recent years, many of the latest electronic assembly and rework applications have very high thermal mass joints on circuit boards with ground planes, or incorporate a very high degree of miniaturization where access to the electronic components and joints is quite limited. In these situations, conventional soldering irons may not provide sufficient heating capability or responsiveness or their relatively bulky heaters and tips do not allow the operator to easily view and solder smaller joints in hard to reach, tight places. In very high through-put electronic production environments, operator comfort, ease of use and efficiency can also suffer due to the relatively large physical dimensions of the handpiece itself, the relatively long distance between the grip portion of the handpiece and the working end of the soldering tip, and the build-up of heat in the handle due to the proximity of the heater to the grip. In addition, many of these soldering stations feature operator selected temperature control which, in some manufacturing environments with relatively unskilled operators, has become a less desirable feature as the supervisor prefers that the operator solder at one specified temperature.
For all the reasons, tip/heater cartridge stations, with their attendant advantages outlined above have become quite popular, particularly in the large contract manufacturing environments. However, because tip life (either conventional tips or tip/heater cartridges) is limited by several factors, such as tip operating temperature, iron plating thickness, solder flux composition and other factors, these tips must be replaced quite frequently, sometimes as often as once per day depending on usage. While conventional soldering tips are relatively inexpensive as discussed above, replacing of tip/heater cartridges can be quite expensive as these cost anywhere from upwards of $12 to $24 dollars each or more.
It is therefore a primary object of the present invention to create an easily replaceable tip end which attaches to the end of an easily replaceable heater cartridge such that only the tip end needs to be replaced at a fraction of the cost of replacing a traditional tip/heater cartridge while offering all or most of the advantages of a tip/heater cartridge.
It is another primary object of the present invention to create a soldering iron with an inexpensive, easily replaceable heater cartridge which uses inexpensive, easily replaceable tips.
It is yet another primary object of the present invention to provide an easily replaceable, inexpensive heater cartridge which offers improved heat transfer and responsiveness over conventional soldering irons (such as by providing the heater bobbin with a silvered end portion on which the tip end seats).
A further object of the present invention is to provide an easily replaceable, inexpensive heater cartridge and tip combination which offers improved physical dimensions (such as a short tip-to grip for better control, and a thin heater and tip for easy access and viewing in tight spaces) in addition to improved heat transfer and responsiveness relative to conventional soldering irons.
It is still another object of the present invention to provide an easily replaceable, inexpensive heater cartridge and tip combination which offers improved comfort to the operator by keeping the heat of the handpiece well away from the grip portion thereof.
These and other objects are achieved by the provision of a heater cartridge composed of a stainless steel tube, a ceramic-potted heater assembly contained within a cylinder closed at one end which is either squared off or tapered and made from a high thermal conductivity material, such as silver, and wherein the heating element is connected to a dissimilar metal which forms a thermocouple, also containing cold lead wires of greater cross-sectional area than the heating element, an end insert which supports and fixes electrical contacts, and wire insulation. The heater cartridge accommodates a replaceable tip which slips over the closed end and is retained, e.g., by a spring, clip, internal thread mating to an external thread on the heater, a pin on the heater and track on the tip, interference fit between tip and heater, or other means.
The heater cartridge with slip-on tip offers an economic advantage to its users. The user can have several heater cartridges and slip-on tips so that when a new or alternate tip is required, the heater cartridge with slip-on tip is removed and a cool heater cartridge (with a replacement slip-on tip already attached) is installed into to the iron. The user need not inventory a large number of tip heater cartridges, but instead needs only a few heater cartridges at each station. Inexpensive slip-on tips can be inventoried at substantially lower cost and require less storage space than their costly tip heater cartridge counterparts.